Using my Sony A77 and 18mm lens I could not fit this curving path and the castle in to frame as there are buildings right at my back. I purchased a wide angle lens Sony's 11-18mm but Sigma do a 10-20mm that is very popular aswell.

Crop Sensor, your sensor size needs to be taken account at this point as my camera has a crop sensor my 18mm lens is actually 27mm and 11mm is 15.5mm. On a camera such as Canon 5D range that have a larger sensor 16mm is actually 16mm.